Fire and overheat detection system

ABSTRACT

A fire and overheat detection system having a tubular sensor with one end closed and one end open and having both a primary responder and a secondary responder, which is a confirmation responder. The primary responder has an electrically conductive primary diaphragm dividing a housing into a first chamber connected to an open end of the sensor and a closed and sealed second chamber. The first chamber is provided with a first electrode with which the primary diaphragm is normally in contact. The primary diaphragm is actuated by pressure different from the ambient pressure to move away from this first electrode. The confirmation responder likewise has a confirmation diaphragm dividing its housing into a third chamber and a fourth chamber, the fourth chamber being connected to the open end of the sensor also. A second electrode in one of these two chambers, that is the third or fourth chamber, is normally against the diaphragm and is moved away from it when the sensor reaches ambient pressure.

[ July 22, 1975 FIRE AND OVERHEAT DETECTION SYSTEM [76] Inventor: John E. Lindberg, 121] Upper Happy Valley Rd., Lafayette, Calif. 94549 22 Filed: Sept. 14, 1973 21 Appl. No.: 397,441

52 U.S. c1. 340/229; 337/309; 337/320; 337/332; ZOO/81.5 [51] Int. Cl. ..H0. .h 37/40 [58] Field of Search 340/227, 227.1, 228, 229; ZOO/81.5; 73/368, 368.2, 368.3; 337/299, 307, 308, 320, 332, 309

Primary Examiner.1ohn W. Caldwell Assistant ExaminerWilliam M. Wannisky Attorney, Agent, or Firm--Owen, Wickersham & Erickson 5 7] ABSTRACT A fire and overheat detection system having a tubular sensor with one end closed and one end open and having both a primary responder and a secondary responder, which is a confirmation responder. The primary responder has an electrically conductive primary diaphragm dividing a housing into a first chamber connected to an open end of the sensor and a closed and sealed second chamber. The first chamber is provided with a first electrode with which the primary diaphragm is normally in contact. The primary diaphragm is actuated by pressure different from the am- [56] References Cited bient pressure to move away from this first electrode.

UNITED STATES ATE The confirmation responder likewise has a confirma- 2,986,9l0 6/1961 Bochan: 200/8l.5 X tiOn diaphragm dividing its housing into a third Cham- 3,234,537 2/1966 Lindberg 340/229 ber and a fourth chamber, the fourth chamber being 3,380,045 4/1968 Lindberg 340/227 R connected to the open end of the sensor also, A see- 3,390,365 6/l968 Lfndberg 349/229 X 0nd electrode in one of these two chambers, that is 3,760,393 9/1973 L ndberg 340/229 the third or fourth chamber, i ly against the 3,766,536 10/1973 H116 340/229 diaphragm and is moved y from it when the Sensor reaches ambient pressure.

8 Claims, 2 Drawing Figures 28V TE ET TE ST 1 FIRE AND OVERI-IEAT DETECTION SYSTEM BACKGROUND OF THE INVENTION provement on or a variation of the device shown in my copending US. patent application Ser. No. 257,437

filed May 26, 1972.

One of the problems to which the invention is directed occurs in a Lindberg type of fire-detection system having a sensor containing a gas at a pressure above atmospheric. In such systems, when one portion of the sensor is at a high temperature and another portion is still at a low temperature, the emission of gas in the high temperature portion of a hydride wire contained in the sensor tube and relied upon to provide high pressure at the responder under these conditions, is sometimes nullified by absorption of this gas elsewhere in the system where the hydride is cooled. To replace the gas at above atmospheric pressure in the sensor with gas below atmospheric pressure does not give fully satisfactory results, because the purpose of having the high pressure inside the sensor was that if there should be a leak in the sensor, the pressure inside would drop rather than giving a false warning. If the pressure inside the sensor is low, then in a conventional Lindberg sensor there is danger that a leak to the atmosphere would increase the pressure above the actuation point and givea false alarm when what should be obtained is a fault alarm. In other words, the standard system employing a pneumatic sensor is modified to change the pressure inside the sensor tube from above atmospheric to below atmospheric. There is a risk that a false fire warning will be obtained by a leak in the sensor. This problem cannot thus be solved by changing the pressure inside the sensor. However, the present system does solve the problem by providing in combination a sensor and two responders, one a primary responder and the other a confirmation responder.

The sensor-responder structure used by the present invention may be that shown in my application Ser. No. 257,437 referred to above. The present invention employs a novel type of electrical connection and a novel location of electrodes to obtain highly superior results.

SUMMARY OF THE INVENTION An important purpose of this system is to provide a rapid response to high temperatures whether they affect only a short portion of the sensoror affect a longer portion. The purpose may be accomplished by the use of two different sensors, as shown in application Ser. No. 257,437, or even with a single sensor and dual responders, as also shown in that same application. However, the structures there provided work in a particular manner, and the present invention provides a different type of double responder system. Here, the tubular sensor is connected both to a primary responder and to a confirmation responder.

The primary responder has aprimary diaphragm that divides the housing into two chambers in one of which is an electrode, the other chamber being closed and sealed. The diaphragm is normally .in contact with the electrode but is actuated by alarm pressures to move away from it. The confirmation responder has a confirmation diaphragm which is also electrically conductive and divides its housing into a pair of chambers, at least one of which (and in some instances both of which) contain electrodes. The diaphragm normally lies against one of these electrodes, and there may be only one of them, and moves away from it when the sensor is punctured or otherwise defective so that the pressure drops to the ambient pressure and changes the pressure in the responder.

The electrode in the primary responder, the diaphragm in the confirmation responder, and an alarm network are connected in parallel to a source of electrical power. The opposite end of the alarm system is grounded and so are the diaphragm in the primary responder and the electrode in the confirmation responder against which the diaphragm normally rests. If there be a second electrode in the confirmation responder it may also be grounded. Each of the grounding circuits connected to a responder may be opened for test purposes. A fault-warning device is provided in parallel with the confirmation responder.

The opening of the confirmation responder causes the fault-warning system to work, since it is set on a threshold where it cannot work as long as the confirmation diaphragm is grounded. Similarly, the alarm system cannot be actuated even though it is connected to the power source so long 'as the first electrode is connected to the grounded primary diaphragm. However, when a lot of pressure causes the diaphragm to move away from this first electrode, the alarm system then receives the actuating power and gives the alarm signal. Various types of circuits carrying this structure out may be provided, and some examples are given below.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a circuit diagram embodying one form of the present invention.

FIG. 2 is a circuit diagram embodying another form of the present invention.

DESCRIPTION OF SOME PREFERRED EMBODIMENTS The Fire and Overheat Device of FIG. 1

The system of FIG. 1 embodies the use of a Lindbergtype sensor 10 which is a hollow tube closed at its outer end 1 1 and connected at its inner end to both a primary responder 12 and a confirmation responder 13. The sensor 10 may be any of the Lindberg sensors; it may have gas inside and may preferably have in addition a hydride wire of a type which liberates large quantities of gas when subjected to temperatures above a predetermined threshold temperature. Basically, it is a type of device in which the sensor reacts to certain temperatures by an increase of gas pressure, the hydride system giving an especially vigorous response even in a portion only of the system.

The primary responder 12 is divided by an electrically conductive primary diaphragm 14, preferably metal and preferably operating with a snap action, into two chambers-a first chamber 15 which is connected to the sensor 10 and a second sealed and closed chamber 16, retained at some convenient predetermined pressure. The first chamber 15 contains an electrode 17 against which the diaphragm 14 normally rests.

The confirmation responder 13 is basically similar to the primary responder 12. It has an electrically conductive diaphragm 20 like the diaphragm 14 dividing a housing of the confirmation responder 13 into a chamber 21 which is in communication with the sensor and a sealed and closed chamber 22. The chamber 22 contains a second electrode 23, and in this form of the invention there is also a third electrode 24 in the chamber 21. The diaphragm is normally urged against the electrode 23 by the pressure in the chamber 21.

It will be apparent from this simple description that the primary diaphragm 14 remains in contact with the first electrode 17 until some predetermined pressure is reached which acts, usually with a snap action, to move the diaphragm 14 away from the first electrode 17. This increase in pressure will not move the conformation responder 20, but a drop in pressure (which would occur if the sensor 10 were damaged and open and to the atmosphere) will cause a drop in pressure sufficient to move the diaphragm 20 away from the electrode 23 and, if the drop is large enough, will move it into contact with the third electrode 24. However, this would not happen unless there were a belowatmospheric condition.

A source 25 of current, which may be a 28-volt battery or some other such system, sends power through a circuit breaker 26 and a load resistor 27 to three leads 28, 29 and 30. The lead 28 goes to the first electrode 17; the lead 29 goes through a resistor 31 to the confirmation diaphragm 20; the third lead goes to an alarm device 32 which may include a bell 33 connected to the ground 34 and may also include warning lamps 35 and 36 (or any desired network of lamps; there may be one or there may be several) all connected to ground at 37.

The primary diaphragm 14 is connected to ground via a lead 40 going to ground at 41. Similarly, the second electrode 23 and the third electrode 24 are connected by a lead 42 to ground at 43. Also, a lead 44 in parallel with the lead 29 is connected to a fault warning device 45 which may comprise a network of lamps 46 and 47 connected to ground at 48.

The device may be provided with a test system in which there are two switches 50 and 51, one switch 50 opening the connection of the lead 40 to ground and the other switch 51 opening the connection of the lead 42 to ground.

It will be apparent from the above description that under normal conditions the power from the source 25 goes to the first electrode 15 via the lead 28 and from there via the primary diaphragm l4 and the lead 40 to ground at 41. Simultaneously it also goes via the lead 29 and resistor 31 to the confirmation diaphragm 20 and, since this normally rests against the second electrode 23, also goes to ground at 43 via the lead 42.

When the primary diaphragm 14 is moved away from the first electrode 17 by a significant pressure increase in the sensor 10 and chamber 15, the current no longer passes from the first electrode 17 to ground; therefore the alarm device 31 is then actuated, the resistor 31 adding enough load to the lead 29 so that the alarm lamps 35 and 36 light and the bell 33 sounds.

As for the fault warning device 45, it is actuated when the diaphragm 20 is not against either electrode :23 or 24 and is therefore not grounded. The test switches 50 and 51 enable the opening of the circuit from ground to test what will happen when the connection to ground is broken.

The System of FIG. 2

The same sensor 10 and same primary diaphragm 12 are employed as in FIG. 1 and the general power system is the same, with like numerals used for like parts.

A confirmation responder has a diaphragm 61 providing two chambers 62 and 63. The chamber 62 is connected to thesensor l0, and there is an electrode 64 in the sealed chamber 63. The electrode 64 is connected by a lead 65 to the lead 40 and thus to ground. The lead 65 also goes to a relay or solid state trigger circuit 66 (which may include a SCR) and thereby to a fault warning system 45.

Operation of the FIG. 2 device will be apparent from what has been said about FIG. 1.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. A fire and overheat detection system including in combination:

tubular sensor means having one end closed and one end open,

a primary responder having a housing and an electrically conductive primary diaphragm dividing said housing into (1) a first chamber connected to an open end of said sensor means, and (2) a closed and sealed second chamber, said first chamber being provided with a first electrode, said primary diaphragm normally being in contact with the electrode, and actuated to move away from it at a pressure which is different from the pressure normally in said sensor means, and

a confirmation responder having a housing and an electrically conductive confirmation diaphragm dividing its said housing into a third chamber and a fourth chamber connected to said open end of said sensor means, and a second electrode in one of said third and fourth chambers against which said diaphragm is normally seated and from which it moves away when said sensor reaches ambient pressure.

2. The system of claim 1 having a third electrode in said chamber of said confirmation responder other than that containing said second electrode, the pressure in its said chambers being adjusted so that, whether said sensor is normally above or below said ambient pressure, said confirmation diaphragm will be normally seated against a said electrode and will not be seated against either said electrode at ambient pressure.

3. A fire and overheat detection system including in combination:

tubular sensor means having one end closed and one end open,

a primary responder having a housing and an electrically conductive primary diaphragm dividing said housing into (1) a first chamber connected to an open end of said sensor means, and (2) a closed and sealed second" chamber, said first chamber being provided with a first electrode, said primary diaphragm normally being in contact with the electrode, and actuated to move away from it at a pressure which is different from the pressure normally viding its said housing into a third chamber and a fourth chamber connected to said open end of said sensor means, and a second electrode in one of said third and fourth chambers against which said diaphragm is normally seated and from which it moves away when said sensor reaches ambient pressure,

a power source connected to said first electrode and to said confirmation diaphragm in parallel through a biasing impedance,

ground means connected to each of said primary diaphragm and said second electrode,

alarm means connected between said power source and ground, in parallel with said first electrode and actuated when said first electrode is out of contact with said primary diaphragm and is therefore not grounded, and

a fault indicator connected in parallel with said confirmation diaphragm and between said power source and ground,

said fault indicator being actuable when said confirmation diaphragm is out of contact with said second electrode and is therefore not grounded.

4. A fire and overheat detection system including in combination:

tubular sensor means having one end closed and one end open,

a primary responder having a housing and an electrically conductive primary diaphragm dividing said housing into (1) a first chamber connected to an open end of said sensor means, and (2) a closed and sealed second chamber, said first chamber being provided with a first electrode, said primary diaphragm normally being in contact with the electrode, and actuated to move away from it at a pressure which is substantially higher than the pressure normally in said sensor means, and

a confirmation responder having a housing and an electrically conductive confirmation diaphragm dividing its said housing into a third chamber and a fourth chamber connected to said open end of said sensor means, and a second electrode in one of said third and fourth chambers against which said diaphragm is normally seated and from which it moves away when said sensor reaches ambient pressure.

5. A fire and overheat detection system including in combination:

tubular sensor means having one end closed and one end open,

a primary responder having a housing connected to an open end of said sensor means and having first pressure-responsive means, and

a confirmation responder having a housing connected to said open end of said sensor means and having second pressure-responsive means,

said first pressure-responsive means being a first electrically conductive diaphragm, said primary responder having a first electrode isolated electrically from said first diaphragm and away from which said first diaphragm moves to actuate a warning, said first diaphragm normally being in contact with said first electrode except when actuated by a predetermined increase of pressure in said sensor,

said second pressure-responsive means being a second electrically conductive diaphragm electrically isolated from said first diaphragm, said confirmation responder having an electrode against which said second diaphragm normally rests, except when moved away therefrom by an abnormal drop of pressure in said sensor.

6. A fire and overheat detection including in combi nation:

tubular sensor means having one end closed and one end open,

a primary responder having a housing connected to an open end of said sensor means and having first pressure-responsive means, and

a confirmation responder having a housing connected to said open end of said sensor means and having second pressure-responsive means,

said first pressure-responsive means being a first metal diaphragm, said primary responder having a metal housing electrically connected to said first diaphragm and a first electrode isolated electrically from said housing and away from which said first diaphragm moves to actuate a warning, said first diaphragm normally being in contact with said first electrode except when actuated by an increase of pressure in said sensor,

said second pressure-responsive means being a second metal diaphragm electrically isolated from said first diaphragm, said confirmation responder having a metal housing electrically connected to said second diaphragm and an electrode against which said second diaphragm normally rests, except when moved away therefrom by an abnormal drop of pressure in said sensor.

7. The system of claim 6 having:

a current source connected by parallel leads to each of said first electrode and, through a resistor, said confirmation electrode,

means connecting each of said primary diaphragm and said second electrode to ground, and

an alarm system connected to said current source in parallel with said first electrode and said confirmation diaphragm and connected to ground and offering little enough resistance so that when said primary diaphragm is ungrounded, said alarm system is actuated, even though said confirmation diaphragm is still grounded.

8. The system of claim 6 wherein:

a fault indicator is connected in parallel with said confirmation diaphragm and between said power source and ground,

said fault indicator being actuable when said confirmation diaphragm is out of contact wth said second electrode and is therefore not grounded. 

1. A fire and overheat detection system including in combination: tubular sensor means having one end closed and one end open, a primary responder having a housing and an electrically conductive primary diaphragm dividing said housing into (1) a first chamber connected to an open end of said sensor means, and (2) a closed and sealed second chamber, said first chamber being provided with a first electrode, said primary diaphragm normally being in contact with the electrode, and actuated to move away from it at a pressure which is different from the pressure normally in said sensor means, and a confirmation responder having a housing and an electrically conductive confirmation diaphragm dividing its said housing into a third chamber and a fourth chamber connected to said open end of said sensor means, and a second electrode in one of said third and fourth chambers against which said diaphragm is normally seated and from which it moves away when said sensor reaches ambient pressure.
 2. The system of claim 1 having a third electrode in said chamber of said confirmation responder other than that containing said second electrode, the pressure in its said chambers being adjusted so that, whether said sensor is normally above or below said ambient pressure, said confirmation diaphragm will be normally seated against a said electrode and will not be seated against either said electrode at ambient pressure.
 3. A fire and overheat detection system including in combination: tubular sensor means having one end closed and one end open, a primary responder having a housing and an electrically conductive primary diaphragm dividing said housing into (1) a first chamber connected to an open end of said sensor means, and (2) a closed and sealed second chamber, said first chamber being provided with a first electrode, said primary diaphragm normally being in contact with the electrode, and actuated to move away from it at a pressure which is different from the pressure normally in said sensor means, a confirmation responder having a housing and an electrically conductive confirmation diaphragm dividing its said housing into a third chamber and a fourth chamber connected to said open end of said sensor means, and a second electrode in one of said third and fourth chambers against which said diaphragm is normally seated and from which it moves away when said sensor reaches ambient pressure, a power source connected to said first electrode and to said confirmation diaphragm in parallel through a biasing impedance, ground means connected to each of said primary diaphragm and said second electrode, alarm means connected between said power source and ground, in parallel with said first electrode and actuated when said first electrode is out of contact with said primary diaphragm and is therefore not grounded, and a fault indicator connected in parallel with said confirmation diaphragm and between said power source and ground, said fault indicator being actuable when said confirmation diaphragm is out of contact with said second electrode and is therefore not grounded.
 4. A fire and overheat detection system including in combination: tubular sensor means having one end closed and one end open, a primary responder having a housing and an electrically conductive primary diaphragm dividing saiD housing into (1) a first chamber connected to an open end of said sensor means, and (2) a closed and sealed second chamber, said first chamber being provided with a first electrode, said primary diaphragm normally being in contact with the electrode, and actuated to move away from it at a pressure which is substantially higher than the pressure normally in said sensor means, and a confirmation responder having a housing and an electrically conductive confirmation diaphragm dividing its said housing into a third chamber and a fourth chamber connected to said open end of said sensor means, and a second electrode in one of said third and fourth chambers against which said diaphragm is normally seated and from which it moves away when said sensor reaches ambient pressure.
 5. A fire and overheat detection system including in combination: tubular sensor means having one end closed and one end open, a primary responder having a housing connected to an open end of said sensor means and having first pressure-responsive means, and a confirmation responder having a housing connected to said open end of said sensor means and having second pressure-responsive means, said first pressure-responsive means being a first electrically conductive diaphragm, said primary responder having a first electrode isolated electrically from said first diaphragm and away from which said first diaphragm moves to actuate a warning, said first diaphragm normally being in contact with said first electrode except when actuated by a predetermined increase of pressure in said sensor, said second pressure-responsive means being a second electrically conductive diaphragm electrically isolated from said first diaphragm, said confirmation responder having an electrode against which said second diaphragm normally rests, except when moved away therefrom by an abnormal drop of pressure in said sensor.
 6. A fire and overheat detection including in combination: tubular sensor means having one end closed and one end open, a primary responder having a housing connected to an open end of said sensor means and having first pressure-responsive means, and a confirmation responder having a housing connected to said open end of said sensor means and having second pressure-responsive means, said first pressure-responsive means being a first metal diaphragm, said primary responder having a metal housing electrically connected to said first diaphragm and a first electrode isolated electrically from said housing and away from which said first diaphragm moves to actuate a warning, said first diaphragm normally being in contact with said first electrode except when actuated by an increase of pressure in said sensor, said second pressure-responsive means being a second metal diaphragm electrically isolated from said first diaphragm, said confirmation responder having a metal housing electrically connected to said second diaphragm and an electrode against which said second diaphragm normally rests, except when moved away therefrom by an abnormal drop of pressure in said sensor.
 7. The system of claim 6 having: a current source connected by parallel leads to each of said first electrode and, through a resistor, said confirmation electrode, means connecting each of said primary diaphragm and said second electrode to ground, and an alarm system connected to said current source in parallel with said first electrode and said confirmation diaphragm and connected to ground and offering little enough resistance so that when said primary diaphragm is ungrounded, said alarm system is actuated, even though said confirmation diaphragm is still grounded.
 8. The system of claim 6 wherein: a fault indicator is connected in parallel with said confirmation diaphragm and between said power source and ground, said fault indicator being actuable when said confirmation diaphragm is out of contact wth said second electrode and is therefore not grounded. 